Schoolboy son Baltic citizen expels (7)
I believe the answer is:
etonian
'schoolboy' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for etonian that I've seen before include "Public schoolboy" , "student in establishment?" , "Relating to one particular school" , "Public school boy" , "Alumnus of famous English school" .)